Charles e



(No Model) E 0. E. SORIBNER.

TELEPHONE EXCHANGE APPARATUS Patented Nov Z1, 1898'.

' INVENTOR j; fiarlesZSar/ner wm /amg I WITNESSES (Li/m ix m UNITED STATES PA NT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGN OR TO WESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters IPatent No. 509,186, dated November 21, 1893. Application filed February 21, 1893- Serial No. 463,222. (No model.)

To all whom it may concern.- provided with a pivoted armature a opposite Be it known that I, CHARLES E. SORIBNER, its poles, and a pivoted indicating shutter a acitizen of'the United States, residing at Chithe latter being normally engaged and held cago, in the county of Cook and State of Illiin its vertical position by a catch a con- 5 nois, have invented a certain new and useful trolled by the armature a, but being adapted Improvement in Telephone-Exchange Appato fall into a horizontal position when disenratus, (CaseNo. 322,) of which the following is gaged. Upon the core a of the annunciator afull, clear, concise,and exact description,refis wound the usual helix 0. of fine wire. erence being had to the accompanying draw- Encirclingthe core at its extremity, nearest :0 ings, forming a part of this specification. the. armature a, is a cylinder or thick tube My invention relates to telephone exchange 0. of copper; and outside of this, next the arswitch board apparatus, and consists, first, in mature, is placed a thin disk or washer a of a clearing out annunciator adapted to reiron. spond to pulsating currents and continuous In the operation of this device a continu- 15 currents, but not to currents of the alternatous current finding circuit through the coil of ing type, which annunciator is adapted to be magnetizes the coil 0, the lines of force findincluded between a pair of telephone lines at ing a return circuit therefrom through the the central office to serve as a clearing out armature a and the shell of the tubular elecannunciator. tromagnet, a small proportion of them being 20 My invention consists, second, in telephone shunted from the armature by the thin iron lines extending each from a subscribers stadisk of; hence the armature is attracted, distion thereon to the central office, a switching engaging the shutter a and the latter falls apparatuscombinedwithaclearingoutannuninto its horizontal position. Again, when a ciator, said annunciator being adapted to repulsating current of constant .direction trav- 25 spondto continuousor pulsating currents,but erses the helix a the latter tends to magnot to alternating currents sent over the lines netize the core a, as before, but the first pulsawith whichthe annunciator maybe connected. tion of the magnetism generates a current in This annunciator may be connected at the the cylinder a which opposes the further central office between the different sides of magnetization of the core. Most of the lines 0 the circuit formed by connecting two teleof force set up in the nearly closed magnetic phone lines together, and when so connected, circuit of the coil persist, however, and the while serving its function of a clearing out magnetizing force of the succeeding pulsasignal receiving instrument to respond to contion of current encounters less opposition. tinuous current or pulsating current, as the Thus successive pulsations of current finally 3 5 case may be, sent over the circuit from either produce a full magnetization of the core, and 8 subscribers station, does not permit the voice the armature is attracted, releasing the shutcurrents or telephonic currents to be shunted ter as before. On the other hand, when an through the same from one side of the ciralternating current finds circuit through the cuit to the other; nor will the said annunhelix a", each pulsation or half wave of our- 0 ciator respond so as to be operated by any alrent produces an induced current in the cop- 9o ternating currents that may be sent to line. per cylinder, tending to demagnetize the core,

In the drawings which are illustrative of or that extremity of it which is most immemy invention, Figure 1 is a side elevation of diately influenced by the copper cylinder; my annunciator. Fig. 2 isalongitudinal cenand as each pulsation or half wave diifers in 5 tral sectional view thereof. Fig.3 represents direction from the preceding pulsation, its 5 diagrammatically the line circuits extending magnetizing effect is opposed not only by the from two substations to the switching appacounter effect of the current in the copper ratus at the central office. cylinder, but also by the more or less intense The annunciator, as illustrated in Figs. 1 magnetization of the core in theopposite di- 50 and 2 comprises a tubular electromagnet a, rection. Thus the alternatingcurrent produces but a very feeble magnetization of the core, and the armature remains inert.

The copper cylinder constitutes a mass of metal of low magnetic permeability, which is adapted to be threaded by the magneticlines of force of the magnet. In Fig. 3 are shown two substations 1 and 2 connected by telephone line circuits 1) b and c 0', respectively, with springjacks and annunciators at the central office. The substations are equipped with apparatus of ordinary character.

A telephone set cl is provided, a calling generator d with its switch key, a signal bell d and a switch 61 The circuit connections are so arranged that when the telephone rests upon the switch hook 01 the bell d and the calling generator d are connected in circuit between the different sidesb bof the line circuit,but when the telephone is removed from the hook, as shown in the drawings, the bell and generator are disconnected from the line, and the telephone and microphone are connected with it. The generator is so connected with its switch key that in the normal position of the latter, alternating currents are sent to line when the generator is operated; but when the key is depressed, the springs thereof are connected with a commutator upon the generator and receive a pulsating current of continuous direction.

The line circuit 1) b is shown connected with two spring-jacks e and e, which may be assumed to be upon different sections f and f of a multiple switchboard, and with a calling annunciator g which is supposed to be located upon the section f of the switchboard. The line circuit 0 c from substation 2 is likewise connected with two springjacks e e and with an annunciator g, which, however, is placed at the switchboardf so as to be under the care of a different attendant. The lines are shown connected together into a continuous metallic circuit through connecting cords at the section f of the switchboard by means of the terminal plugs h h of the cord circuit and the springjacks of the different lines. Each terminal plug is pro- Vided with contact pieces adapted to make connection with corresponding contact pieces of a springjack into which it may be inserted; like contact pieces of two plugs h h are connected together by means of conductors t 11. Two calling keys is and have their contact points included in the cord circuit?) 2" so that by depressing the corresponding key either plug it or 72' may be disconnected from the other and connected with the poles Z Z of a calling generator, not shown, to send calling signals over a line with which the cord is connected. A telephone set m is provided for the attendant operator, connected with contact points of a listening key n by which she is enabled to connect the telephone with the cord circuit, or to disconnect it therefrom.

To that strand of the connecting cord which joins the sleeves of the two connecting plugs one pole of a battery 0 is connected, the other pole being grounded; a retardation coil p is included in the branch between the battery and the cord circuit in order that when several cord circuits are connected with the same battery 0, leakage of telephonic currents from one cord circuit to another shall be prevented. This battery is provided for testing purposes, its function being to electrify the exposed ferrules or test rings of all the springjacks of the line to which the cord circuit is connected, to a difference of potential from the earth,in order that an operator at another switchboard may determine that the line is in use before attempting to make connection with it, by testing the electrical condition of the test rings of the line by means of agrounded tele phone. A clearing-out annunciator q, such as that shown in Figs. 1 and 2 and hereinbefore described, is permanently connected in a bridge or branch circuit between the different sides t' t of the cord circuit.

In the normal condition of the line circuits no connecting plug is inserted into anyspringjack of the line. A subscriberfor example, subscriber at station ldesiring to have connection established between his line and some other terminating at the central office, rotates his calling generator, sending a signaling cur rent over the lines I) b, which finds circuit through the annunciator g at the central office. The annunciator is thus actuated and indicates the signal to the operator at the section f of the switchboard. The operator thereat at once inserts one plug it of a pair into the springjack 6, whereby the annunciatorg is disconnected from the line circuit, and the circuit from station 1 is continued to the cord circuit 2' 2". The operator then depresses the plunger of her listening key it, connecting her telephone with the cord circuit, and receives the order for the connection desired,-in this instance, with the line to station 2. She then tests the springjack of that line at her section f of the switchboard to determine whether the line is already in use or not, by applying the tip of the other plug it of the pair to the thimble or test ring of the springjack e If the line be already in use, the test rings are connected at some other switchboard with a grounded battery 0, and hence a current will find circuit from the test ring through the telephone of the operator making the test, and will give a click in the telephone which will signify to the operator that the line is already in use. Assuming, however, that the operator finds the line to station 2not in use, sheinserts the other connecting plug 77. of the pair fully into the springjack 6 whereby the circuit of the annunciator g of that line is opened, and the line circuit is connected with corresponding portions of the cord circuitt' t". The two substations are now connected together in a continuous metallic circuit. The operator may send a calling signal to station 2 by depressing the plunger of ringing key 71:, and when the subscriber at station 2 has responded and ICC removed his telephone from its switch hook, thev apparatus is in position to permit of communication between the. two subscribers. The operator, after sending the calling signal', disconnects her telephone set from the cord circuit and proceeds to attend to other business. If, however, the subscriber at station 2 fails to respond to the call signal sent by the operator, the subscriber at station 1 may replace his telephone upon the switch hook, and, without depressing the key of his generator, may again rotate his generatorv to send an alternating current upon the lines. This current will find circuit to station 2 and will operate the call bell thereat; a portion of the signaling current will be shunted through the clearing-out annunciator q, but will not operate this annunciator, as explained in connection with Figs. 1 and 2. When the subscribers have finished their conversation, either of them may send a pulsating signaling current upon the line circuit by rotating his generator, and, at the same time, depressing the key, which pulsating current, finding circuit through the annunciator q, will operate the same and indicate the signal for disconnection to the attendant operator,who will thereupon remove the plugs from the springjacks.

In some exchange systems it is customary for the calling subscriber to send the call signal over the completed circuit to the station with which his line is connected, the operator merely establishing connection between the two lines. My invention is particularly useful in such a case. The calling keys is and It may then be omitted, if desired, the operator simply establishing connection between two lines in response to a request from the subscriber of one of them, and informing the calling subscriber that such connection has been made; the calling subscriber then sends an alternating calling current upon the line to call the subscriber with whom he is connected.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The combination with two telephone lines each extending from a substation to a central station, of conductors joining the telephone lines at the central station, and a clearing-out drop connected with the said conductor comprising an electromagnet having a movable armature for completing its magnetic circuit, and an auxiliary closed conducting circuit encircling some portion of said magnetic circuit, whereby alternating signaling currents may be sent over connected lines without operating the clearingout annunciator, substantially as described.

2. The combination with two telephone lines each extending from a substation to a central station, of conductors joining two telephone lines at the central station, a clearingout annunciator connected with the said conductors comprising an electroinagnet and armature therefor, a tube or cylinder of conducting material closely surrounding the core of said electromagnet, and sources of pulsating or alternating signaling current adapted to be connected with the said line, substantially as described.

3. The combination with two telephone lines each extending from a substation to a central station, of a conductor at the central station joining the two telephone lines into a continuous circuit, and a clearing-out annunciator connected in a bridge between the different sides of said circuit, said annunciator being provided with a tube or cylinder of conducting material'closely encircling some portion of its core to prevent the full magnetization thereof by alternating currents, substantially as described.

4. The combination with a cord circuit of a telephone switchboard, of a clearing-out annunciator connected in a bridge between the different conductors or strands of the cord circuit, said bridge circuit being of high resistance and retardation, said annunciator having a conducting tube or cylinder closely encircling a portion of the magnetic circuit of its electromagnet to prevent the full magnetization thereof by alternating currents, and having also a bridge of magnetic material partially completing the said magnetic circuit independently of the armature, substantially as described. 5. The combination with a telephone circuit provided with means for sending calling currents either constant or alternating in direction, of an annunciator connected in a bridge between the different sides of the circuit, said annunciator being arranged to be irresponsive to alternating currents by encircling a portion of the magnetic circuit of its electromagnet by an auxiliary closed conducting circuit, substantially as described.

6. In a telephone exchange system,the combination with a telephone circuit and means for sending current over said circuit of constant direction or of the alternating character, at will, of a clearing out annunciator in a bridge between the different sides of the circuit at the central office, said annunciator being provided with a mass of metal of low magnetic permeability adapted to be threaded by the magnetic lines of force of the magnet of said annunciator; and provided also with a drop controlled by the armature thereof; whereby on sending current of constant direction over the line the drop is thrown down, and whereby voice currents or alternating currents sent over the line are retarded and prevented from passing from one side of IIO the circuit to the other through the bridge,

while the annunciator remains acquiescent, substantially as specified.

7. The combination in an electric annunciator, of the drop or target controlled by the armature lever, the core provided with a copper sent through the helix is expended in producing current in the said copper cylinder, thereby maintaining the pole presented to the armature practically neutral, substantially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 6th day of January, A. D. 1893.

CHARLES E. SCRIBNER.

Witnesses:

ELLA EDLER, A. P. BENNOOK. 

